public class Triangle {
    double sideA,sideB,sideC,area;
    boolean isTriange;
    public String getArea() {
        if(isTriange) {
            double p=(sideA+sideB+sideC)/2.0;
            area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC)) ;
            return String.valueOf(area);
        }
        else {
            return "无法计算面积";
        }
    }
    public void setA(double a) {
        sideA=a;
        if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
            isTriange=true;
        else
            isTriange=false;
    }
    public void setB(double b) {
        sideB=b;
        if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
            isTriange=true;
        else
            isTriange=false;
    }
    public void setC(double c) {
        sideC=c;
        if(sideA+sideB>sideC&&sideA+sideC>sideB&&sideC+sideB>sideA)
            isTriange=true;
        else
            isTriange=false;
    }
}
